Technical Field
The present invention relates to a method and apparatus for displaying caller information during switching of an incoming call in a private branch exchange and, in particular, to a method and apparatus for displaying caller information on a display of an extension terminal during switching of an incoming call.
In general, a private branch exchange (hereinafter referred to as "PBX") switches an incoming call from an office line or an extension line to a specified extension line in response to a call switching request.
In that regard, a PBX system generally includes a PBX, subscriber terminals (i.e., extension telephones), and a control terminal.
The PBX itself can have various configurations, but typically includes at least a controller, a switching circuit, a memory, and a tone generator. As explained in more detail below, such PBX systems have various disadvantages.
For example, the call switching method employed in such PBX systems is typically quite sophisticated, in that an incoming call is switched to a specified extension line in response to a call switching request from an originating central office line or an extension line. Moreover, in such a PBX system, a control terminal sends a ring signal only when switching an incoming call to designated extension line. This result in disadvantage in that, in a order to recognize the caller, the subscriber must answer the switched incoming call. In addition, since the subscriber can not recognize the call before he or she answers the incoming call from the central office line, the subscriber can not handle the incoming call promptly.
U.S. Pat. No. 5,228,073, Smith discloses a call identification display system which includes a reception unit, at least one remote user unit, and a communication link. The reception unit disclosed in this patent has a data entry device for entering a message relative to an incoming caller and a display device, and each remote user unit includes a display device displaying the message from the reception unit identifying the incoming caller, as well as an instructions selector for selecting one of a number of predetermined instruction for display on the display device in the reception unit.
Nevertheless, the disclosure of the patent does not provide a solution to the problems identified herein.
Particularly, there is a need for the development of a call switching method and apparatus which not only allows the subscriber to recognize a caller without answering an incoming call, but also provides for the outputting of caller information through a subscriber terminal, as well as the capability whereby a subscriber can recognize in advance the name of a caller prior to answering an incoming call from a central office line, thereby permitting the subscriber to handle the incoming call promptly.